The datasheet on this is not very clear, it says USB 2.0 or optional GigE output.

If this outputs video in a standard format over USB as a UVC device, or can output data on the network via an ethernet connection, then it should be possible to get the video through the tether. We need more information from the manufacturer.

Good question. The intended use was not so much to “see” better underwater as you might compare it to car mounted or boat mounted camera. My intention is to use it to locate leaks from pipelines or kinks in electrical cables that may cause resistance and thereby thermal heat. A leakage sometimes have a little higher temperature then the surroundings and could be spotted with the Thermal cam.

The phone need to be submerged, I guess, to avoid surface reflection.
Filming through the glass of an aquarium should be possible if you install a small heat source in the water, a resistor or something that will send out a continuous rate of heat. (Your hand probably cool down to much as the blood pulls back due to the cold water, depending on the accuracy of the thermal unit)

Sorry I haven’t had time to get to this yet. All my housings are full of stuff at the moment. I may just have to improvise with a plastic bag and a scrap piece of 1/4" plexiglass. I’ll see what I can do this weekend.

Attached is a link to an example plot for the attenuation of light in seawater. From this you can see that the attenuation of red light attenuation in seawater is 100-500 times that of blue-green light.

This alone does not necessarily mean the IR camera won’t work but it does mean that the thermal signal-to-noise ratio will quickly drop as a function of the range between the thermal target and the camera.

As mentioned above there are simple tests that one might perform to test this.

If you use an incandescent light bulb as a target you could image it directly and indirectly by placing a transparent fish tank between light bulb and camera to see how much the IR is attenuated as a function of range.

You could also test other IR targets such as a soldering iron or a tube ejecting hot water into the tank as a simulated UW pipe leak to determine useful range as a function of water temperature and leakage temp.

Sorry I’m not much help on the analytical side as I am more of an engineer than a physicist.

A real thermal imager (like the one you pointed to) typically functions by measuring in the 7-14 micron wavelength range of IR. The imager simply measures the amount of energy collected within that band; its sensor like an array of tiny energy-collecting buckets, each “bucket” energy level coded to a pixel’s color range. The 7-14 micron band was chosen because there happens to be an “atmospheric window” (through air) in that part of the electromagnetic spectrum such that those particular wavelengths can travel without being absorbed. That way distance doesn’t affect the measured energy.

Turns out that water is almost completely opaque at those wavelengths (it might as well be milk). Even with direct submersion, at best all that you’ll measure is the water touching your (IR transparent) lens.

Parenthetically, most lenses (glass/plastic) are not transparent to those wavelengths of IR. If you’re trying to look through glass/plastic, you’ll mostly measure the glass/plastic. Since you’d of course have to house the camera behind a thick pressure window/dome, the thickness guarantees your IR camera won’t even see the wet side of the window.

As indeed fluids coming out of underwater pipes is often higher in temp … we have used temp probes on handles to detect sudden rises in temps when flying along a pipe. You have to put it fairly close but if your trying to detect a leak its a great and cheap way to get your first detections even if its just to give you a starting point. Often you find heat rising off a pipe anyway so your looking for spikes in environmental conditions.
This of course is dependant on what type of pipe and fluid within your trying to detect., its can easily be not heated at all. Oil and Gas work … likely an option. Detecting a leaking water / sewage pipe … not so much. haha